Frequency hop based positioning measurement

ABSTRACT

Positioning reference signals are transmitted in a downlink direction from base stations (200) of a wireless communication network to a wireless communication device (100) or in an uplink direction from the wireless communication device (100) to base stations (200) of the wireless communication network. According to a frequency hop pattern, a radio interface of the wireless communication device is switched between multiple different frequency ranges. In this way, the wireless communication device (100) can receive the downlink positioning reference signals on multiple different frequencies defined by the frequency hop pattern or send the uplink positioning reference signals on multiple different frequencies defined by the frequency hop pattern.

FIELD OF THE INVENTION

The present invention relates to methods for enabling positioningmeasurements for a device in a wireless communication network and tocorresponding devices and systems.

BACKGROUND OF THE INVENTION

In wireless communication networks, such as a cellular network based onthe LTE (Long Term Evolution) radio access technology specified by 3GPP(3^(rd) Generation Partnership Project), wireless communication devices(also referred to as user equipment or “UE”) can be located on the basisof positioning reference signals (PRS) transmitted in a downlinkdirection from base stations, referred to as eNB (evolved Node B) to theUE. The UE receives the PRS and then performs a timing difference ofarrival (TDOA) measurement on the basis of the received PRS. Themeasurement results are transmitted from the UE to a location server,which estimates the position of the UE from the measurement results. Afurther possibility is to use sounding reference signals (SRS)transmitted by the UE. In this case multiple eNBs may perform TDOAmeasurements on the SRS transmitted by the UE. Also in this case, themeasurement results may be provided to a location server, whichestimates the position of the UE from the measurement results.

The PRS and the SRS are typically distributed over the entire LTE systembandwidth. The mapping of the PRS and the SRS to LTE radio resources isdefined in 3GPP TS 36.211 V13.2 (2016 June). However, this widedistribution may be problematic for certain UE types which do notsupport the entire LTE system bandwidth, e.g., Machine TypeCommunications (MTC) and Narrow-band Internet of Things (NB-IoT)devices. This may for example have the effect that that only a subset ofthe possible PRSs or SRS can be utilized for positioning measurementsand positioning accuracy is reduced.

Accordingly, there is a need for techniques that allow for efficientlyenabling position measurements for a wireless communication device.

SUMMARY OF THE INVENTION

According to an embodiment, a method of enabling position measurementfor a wireless communication device is provided. According to themethod, a frequency hop pattern for receiving downlink (DL) positioningreference signals from base stations of a wireless communication networkis configured. According to the frequency hop pattern, the wirelesscommunication device switches a radio interface of the wirelesscommunication device between multiple different frequency ranges toreceive the DL positioning reference signals on multiple differentfrequencies defined by the frequency hop pattern. By combined evaluationof the received DL positioning reference signals, the wirelesscommunication device determines positioning information for the wirelesscommunication device. Accordingly, the DL positioning reference signalscan be received on frequencies which are distributed over a widefrequency range, even if the radio interface supports only a limitedbandwidth. In particular, even if the radio interface of the wirelesscommunication device supports only a narrow bandwidth within the systembandwidth of the wireless communication network, the DL positioningreference signals may be distributed over a wider frequency range thanthis narrow bandwidth. This may allow for reducing the influence offrequency dependent disturbances, such as frequency selective fading. Asa result, improved positioning accuracy may be achieved.

According to an embodiment, the wireless communication device configuresthe frequency hop pattern for the DL positioning reference signals onthe basis of configuration information received from the wirelesscommunication network. For example, the configuration information may beprovided by one of the base stations. However, it is noted that in somescenarios it is also possible that the wireless communication devicelocally determines the frequency hop pattern and then indicates thefrequency hop pattern to the wireless communication network, e.g., bytransmitting corresponding configuration information to a base stationof the wireless communication network. By transmitting the configurationinformation, the wireless communication device and the wirelesscommunication network may configure the frequency hop pattern for the DLpositioning reference signals in a flexible manner, for example takinginto account current operating conditions.

According to an embodiment, the positioning information comprises atime-difference of arrival of the DL positioning reference signals frommultiple different base stations. Accordingly, a low implementationeffort may be achieved because the measurement results may thus bereported and evaluated in a similar manner as in existing PRS basedpositioning mechanisms.

According to a further embodiment, a method of enabling positionmeasurement for a wireless communication device is provided. Accordingto the method, a frequency hop pattern is configured. The frequency hoppattern is to be applied for switching a radio interface of the wirelesscommunication device between multiple different frequency ranges toreceive DL positioning reference signals on multiple differentfrequencies defined by the frequency hop pattern. A base station of thewireless communication network sends a first part of the DL positioningreference signals according to the frequency hop pattern. Further, thebase station configures further base stations of the wirelesscommunication network to send a second part of the DL positioningreference signals according to the frequency hop pattern.

According to an embodiment, the base station sends configurationinformation indicating the frequency hop pattern for the DL positioningreference signals to the wireless communication device. However, it isnoted that in some scenarios it is also possible that the base stationconfigures the frequency hop pattern for the DL positioning referencesignals based on configuration information received from the wirelesscommunication device. Accordingly, the wireless communication device maylocally determine the frequency hop pattern for the DL positioningreference signals and then indicate the frequency hop pattern to thewireless communication network. By transmitting the configurationinformation, the wireless communication device and the wirelesscommunication network may configure the frequency hop pattern for the DLpositioning reference signals in a flexible manner, for example takinginto account current operating conditions.

According to an embodiment, the base station sends configurationinformation indicating the frequency hop pattern for the DL positioningreference signals to the further base stations. By transmitting theconfiguration information to the further base stations, the frequencyhop pattern for the DL positioning reference signals as applied by thebase station and the further base stations may be configured in aflexible manner, for example taking into account current operatingconditions.

According to a further embodiment, a wireless communication device isprovided. The wireless communication device comprises a radio interfacefor connecting to a wireless communication network. Further, thewireless communication device comprises at least one processor. The atleast one processor is configured to:

-   -   configure a frequency hop pattern for receiving DL positioning        reference signals from base stations of the wireless        communication network;    -   according to the frequency hop pattern, switch the radio        interface of the wireless communication device between multiple        different frequency ranges to receive the DL positioning        reference signals on multiple different frequencies defined by        the frequency hop pattern; and    -   by combined evaluation of the received downlink positioning        reference signals, determine positioning information for the        wireless communication device.

The at least one processor of the wireless communication device may beconfigured to perform the steps of the above method. In particular, theat least one processor may be configured to configure the frequency hoppattern for the DL positioning reference signals on the basis ofconfiguration information received from the wireless communicationnetwork. Further, the at least one processor may be configured todetermine the positioning information to comprise a time-difference ofarrival of the DL positioning reference signals from multiple differentbase stations.

According to a further embodiment, a base station for a wirelesscommunication network is provided. The base station comprises a radiointerface for connecting to a wireless communication device and anetwork interface for connecting to further base stations of thewireless communication network. Further, the base station comprises atleast one processor. The at least one processor is configured to:

-   -   configure a frequency hop pattern to be applied for switching a        radio interface of the wireless communication device between        multiple different frequency ranges to receive DL positioning        reference signals on multiple different frequencies defined by        the frequency hop pattern;    -   via the radio interface of the base station, send a first part        of the DL positioning reference signals according to the        frequency hop pattern; and    -   via the network interface, configure further base stations of        the wireless communication network to send a second part of the        DL positioning reference signals according to the frequency hop        pattern.

The at least one processor of the base station may be configured toperform the steps of the above method. In particular, the at least oneprocessor may be configured to send configuration information indicatingthe frequency hop pattern for the DL positioning reference signals tothe wireless communication device. This may be accomplished via theradio interface. Further, the at least one processor may be configuredto send configuration information indicating the frequency hop patternfor the DL positioning reference signals to the further base stations.This may be accomplished via the network interface.

According to a further embodiment, a system is provided. The systemcomprises a base station according to the above embodiment. Further, thesystem comprises the wireless communication device.

In the above embodiments of a method, wireless communication device,base station, or system, at least some of the multiple differentfrequencies for the DL positioning reference signals may be separated bymore than a maximum bandwidth supported by the radio interface of thewireless communication device. Accordingly, frequency diversity for theDL positioning reference signals may be enhanced beyond the maximumbandwidth supported by the radio interface of the wireless communicationdevice.

The frequency hop pattern for the DL positioning reference signals maydefine a first frequency hop distance which is larger than the maximumbandwidth supported by the radio interface and a second frequency hopdistance which is smaller than the maximum bandwidth supported by theradio interface. In this way, the multiple different frequencies usedfor the DL positioning reference signals may be efficiently distributed.

The frequency hop pattern of the DL positioning reference signals mayfurther define a repetition pattern of the DL positioning referencesignals. By the repetition pattern, repeated transmissions of the DLpositioning reference signal may be utilized for enhancing positioningaccuracy.

The DL positioning reference signals transmitted by different basestations may be multiplexed on the basis of a multiplexing schemecomprising one or more of frequency division multiplexing, time divisionmultiplexing, and code division multiplexing. In this way, availableradio resources may be utilized in an efficient manner. In someembodiments, a frequency granularity for frequency division multiplexingof the DL positioning reference signals transmitted by different basestations may be finer than a frequency granularity for frequencydivision multiplexing of wireless communication signals transmittedbetween the wireless communication device and the wireless communicationnetwork. In this way, available radio resources may be utilized in anefficient manner for transmission of the DL positioning referencesignals.

According to a further embodiment, a method of enabling positionmeasurement for a wireless communication device is provided. Accordingto the method, a frequency hop pattern for sending uplink (UL)positioning reference signals from the wireless communication device isconfigured. According to the frequency hop pattern, the wirelesscommunication device switches a radio interface of the wirelesscommunication device between multiple different frequency ranges to sendthe UL positioning reference signals on multiple different frequenciesdefined by the frequency hop pattern. Accordingly, the UL positioningreference signals can be sent on frequencies which are distributed overa wide frequency range, even if the radio interface supports only alimited bandwidth. This may allow for reducing the influence offrequency dependent disturbances, such as frequency selective fading. Asa result, improved positioning accuracy may be achieved.

According to an embodiment, the wireless communication device configuresthe frequency hop pattern for the UL positioning reference signals onthe basis of configuration information received from the wirelesscommunication network. For example, the configuration information may beprovided by one of the base stations. However, it is noted that in somescenarios, it is also possible that the wireless communication devicelocally determines the frequency hop pattern for the UL positioningreference signals and then indicates the frequency hop pattern to thewireless communication network, e.g., by transmitting correspondingconfiguration information to a base station of the wirelesscommunication network. By transmitting the configuration information,the wireless communication device and the wireless communication networkmay configure the frequency hop pattern for the UL positioning referencesignals in a flexible manner, for example taking into account currentoperating conditions.

According to a further embodiment, a method of enabling positionmeasurement for a wireless communication device is provided. Accordingto the method a frequency hop pattern is configured. The frequency hoppattern is to be applied for switching a radio interface of the wirelesscommunication device between multiple different frequency ranges to sendUL positioning reference signals on multiple different frequenciesdefined by the frequency hop pattern. A base station of the wirelesscommunication network receives the UL positioning reference signals.Further, the base station configures further base stations of thewireless communication network to receive the UL positioning referencesignals and provide information derived from the received UL positioningreference signals to the base station. By combined evaluation of thereceived UL positioning reference signals and the information providedby the further base stations, the determines positioning information forthe wireless communication device.

According to an embodiment, the base station sends configurationinformation indicating the frequency hop pattern for the UL positioningreference signals to the wireless communication device. However, it isnoted that in some scenarios it is also possible that the base stationconfigures the frequency hop pattern for the UL positioning referencesignals based on configuration information received from the wirelesscommunication device. Accordingly, the wireless communication device maylocally determine the frequency hop pattern for the UL positioningreference signals and then indicate the frequency hop pattern to thewireless communication network. By transmitting the configurationinformation, the wireless communication device and the wirelesscommunication network may configure the frequency hop pattern for the ULpositioning reference signals in a flexible manner, for example takinginto account current operating conditions.

According to an embodiment, the base station sends configurationinformation indicating the frequency hop pattern for the UL positioningreference signals to the further base stations. By transmitting theconfiguration information to the further base stations, the frequencyhop pattern for the UL positioning reference signals as applied by thebase station and the further base stations may be configured in aflexible manner, for example taking into account current operatingconditions.

According to an embodiment, the positioning information comprises atime-difference of arrival of the UL positioning reference signals atmultiple different base stations. Accordingly, a low implementationeffort may be achieved because the measurement results may thus bereported and evaluated in a similar manner as in existing SRS basedpositioning mechanisms.

According to a further embodiment, a wireless communication device isprovided. The wireless communication device comprises a radio interfacefor connecting to a wireless communication network. Further, thewireless communication device comprises at least one processor. The atleast one processor is configured to:

-   -   configure a frequency hop pattern for sending UL positioning        reference signals from the wireless communication device; and    -   according to the frequency hop pattern, switch the radio        interface of the wireless communication device between multiple        different frequency ranges to send the UL positioning reference        signals on multiple different frequencies defined by the        frequency hop pattern.

The at least one processor of the wireless communication device may beconfigured to perform the steps of the above method. In particular, theat least one processor may be configured to configure the frequency hoppattern for the UL positioning reference signals on the basis ofconfiguration information received from the wireless communicationnetwork.

According to a further embodiment, a base station for a wirelesscommunication network is provided. The base station comprises a radiointerface for connecting to a wireless communication device and anetwork interface for connecting to further base stations of thewireless communication network. Further, the base station comprises atleast one processor. The at least one processor is configured to:

-   -   configure a frequency hop pattern to be applied for switching a        radio interface of the wireless communication device between        multiple different frequency ranges to send UL positioning        reference signals on multiple different frequencies defined by        the frequency hop pattern;    -   via the radio interface of the base station, receive the UL        positioning reference signals;    -   via the network interface, configure further base stations of        the wireless communication network to receive the UL positioning        reference signals and provide information derived from the        received uplink positioning reference signals to the base        station; and    -   by combined evaluation of the received UL positioning reference        signals and the information provided by the further base        stations, determine positioning information for the wireless        communication device.

The at least one processor may be configured to perform the steps of theabove method. In particular, the at least one processor may beconfigured to send configuration information indicating the frequencyhop pattern for the UL positioning reference signals to the wirelesscommunication device. This may be accomplished via the radio interface.Further, the at least one processor may be configured to sendconfiguration information indicating the frequency hop pattern for theUL positioning reference signals to the further base stations. This maybe accomplished via the network interface.

According to a further embodiment, a system is provided. The systemcomprises a base station according to the above embodiment. Further, thesystem comprises the wireless communication device.

In the above embodiments of a method, wireless communication device,base station, or system, at least some of the multiple differentfrequencies for the UL positioning reference signals may be separated bymore than a maximum bandwidth supported by the radio interface of thewireless communication device. Accordingly, frequency diversity for theUL positioning reference signals may be enhanced beyond the maximumbandwidth supported by the radio interface of the wireless communicationdevice.

The frequency hop pattern for the UL positioning reference signals maydefine a first frequency hop distance which is larger than the maximumbandwidth supported by the radio interface and a second frequency hopdistance which is smaller than the maximum bandwidth supported by theradio interface. In this way, the multiple different frequencies usedfor the UL positioning reference signals may be efficiently distributed.

The frequency hop pattern the UL positioning reference signals mayfurther define a repetition pattern of the UL positioning referencesignals. By the repetition pattern, repeated transmissions of the ULpositioning reference signal may be utilized for enhancing positioningaccuracy.

The UL positioning reference signals transmitted by different wirelesscommunication devices may be multiplexed on the basis of a multiplexingscheme comprising one or more of frequency division multiplexing, timedivision multiplexing, and code division multiplexing. In this way,available radio resources may be utilized in an efficient manner. Insome embodiments, a frequency granularity for frequency divisionmultiplexing of the UL positioning reference signals transmitted bydifferent wireless communication devices may be finer than a frequencygranularity for frequency division multiplexing of wirelesscommunication signals transmitted between the wireless communicationdevice and the wireless communication network. In this way, availableradio resources may be utilized in an efficient manner for transmissionof the UL positioning reference signals.

The above and further embodiments of the invention will now be describedin more detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates positioning measurements based on DLpositioning reference signals according to an embodiment of theinvention.

FIG. 2 schematically illustrates a frequency hop pattern for DLpositioning reference signals according to an embodiment of theinvention.

FIG. 3 schematically illustrates a further frequency hop pattern for DLpositioning reference signals according to an embodiment of theinvention.

FIG. 4 schematically illustrates a further frequency hop pattern for DLpositioning reference signals according to an embodiment of theinvention.

FIG. 5 schematically illustrates a further frequency hop pattern for DLpositioning reference signals according to an embodiment of theinvention.

FIG. 6 schematically illustrates frequency division multiplexing for DLpositioning reference signals according to an embodiment of theinvention.

FIG. 7 schematically illustrates positioning measurements based on ULpositioning reference signals according to an embodiment of theinvention.

FIG. 8 schematically illustrates a frequency hop pattern for ULpositioning reference signals according to an embodiment of theinvention.

FIG. 9 schematically illustrates a further frequency hop pattern for ULpositioning reference signals according to an embodiment of theinvention.

FIG. 10 schematically illustrates a further frequency hop pattern for ULpositioning reference signals according to an embodiment of theinvention.

FIG. 11 schematically illustrates a further frequency hop pattern for ULpositioning reference signals according to an embodiment of theinvention.

FIG. 12 schematically illustrates frequency division multiplexing for ULpositioning reference signals according to an embodiment of theinvention.

FIG. 13 shows a flowchart for illustrating a method according to anembodiment of the invention, which may be implemented by a wirelesscommunication device.

FIG. 14 shows a flowchart for illustrating a further method according toan embodiment of the invention, which may be implemented by a basestation.

FIG. 15 shows a flowchart for illustrating a further method according toan embodiment of the invention, which may be implemented by a wirelesscommunication device.

FIG. 16 shows a flowchart for illustrating a further method according toan embodiment of the invention, which may be implemented by a basestation.

FIG. 17 schematically illustrates a processor-based implementation of awireless communication device according to an embodiment of theinvention.

FIG. 18 schematically illustrates a processor-based implementation of abase station according to an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, exemplary embodiments of the invention will bedescribed in more detail. It has to be understood that the followingdescription is given only for the purpose of illustrating the principlesof the invention and is not to be taken in a limiting sense. Rather, thescope of the invention is defined only by the appended claims and is notintended to be limited by the exemplary embodiments describedhereinafter.

The illustrated embodiments relate to enabling positioning measurementsfor a wireless communication device, in the following also referred toas “UE”. The positioning measurements are based on DL positioningreference signals transmitted by base stations of the wirelesscommunication network and/or on UL positioning reference signalstransmitted by the UE. In order to address the limitations of a radiointerface of the UE, e.g., a bandwidth limitation, transmission andreception of the DL positioning reference signals or UL positioningreference signals is based on a frequency hop pattern which definesmultiple different frequencies. Using this frequency hop pattern, the UEswitches its radio interface between multiple frequency ranges. In thisway, the UE can receive the DL positioning reference signals on multipledifferent frequencies which are not limited by a maximum bandwidthsupported by the radio interface or send the UL positioning referencesignals on multiple different frequencies which are not limited by themaximum bandwidth supported by the radio interface. As a result,frequency diversity for the DL positioning reference signals or for ULpositioning reference signals can be enhanced and positioning accuracyimproved.

FIG. 1 schematically illustrates positioning measurements for a UE 100which are based on DL positioning reference signals 10 transmitted bydifferent base stations 200 of the wireless communication network. Oneof the base stations 200, e.g., the base station designated with “BS1”,is assumed to be a serving base station of the UE 100. Via the servingbase station 200, the UE 100 is connected to the wireless communicationnetwork. The other base stations 200 are assumed to be neighboring basestations.

As illustrated, each of the base stations 200 transmits DL positioningreference signals 10. The DL positioning reference signals 10transmitted by the different base stations 200 may be multiplexed usingfrequency division multiplexing, time division multiplexing, and/or codedivision multiplexing. The DL positioning reference signals 10 can bebased on differential operations between two training symbols and may begenerated based on a Zadoff-Chu sequence. The DL positioning referencesignals 10 may be broadcast signals which can be received by every UEwithin the coverage region of the base station 200. However, it is alsoconceivable to utilize UE-specific DL positioning reference signals.

The UE 100 receives the DL positioning reference signals 10 andevaluates the received DL positioning reference signals 10. For example,the UE 100 may perform cross-correlation of the received DL positioningreference signals 10 with locally generated signals and thereby estimatepropagation delays for the DL positioning reference signals 10. This mayalso involve averaging and/or correlating multiple transmissions of theDL positioning reference signals 10 from the same base station 200. TheUE 100 may, additionally or alternatively, also utilize a PDP (PowerDelay Profile) for estimating the propagation delays of the DLpositioning reference signals 10. From the propagation delays, or thecross correlations, of the DL positioning reference signals 10 from thedifferent base stations 200 the UE 10 may then obtain RSTD (ReferenceSignal Time Difference) values, e.g., by subtracting the propagationdelay obtained for each of the neighboring base stations 200 from thepropagation delay obtained for the serving base station 200.

The UE 100 then reports the measurements, e.g., the obtained RSTDvalues, as positioning information to a location server (notillustrated). This may also involve reporting measurement quality. Thelocation server may then further evaluate the reported measurements todetermine the position of the UE 100, e.g., in terms of geographicalcoordinates. This may for example be based on triangulation and/ortrilateration calculations.

As mentioned above, the transmission of the DL positioning referencesignals 10 is based on a frequency hop pattern. The frequency hoppattern can be configured by the wireless communication network. Thefrequency hop pattern can be base station specific, cell specific, or UEspecific. Accordingly, each base station 200 changes the frequency (f)where it transmits its DL positioning reference signals 10 depending onthe time (t). In other words, at a first time, the base station 200transmits its DL positioning reference signals 10 on a first frequency,while at a second time the base station 200 transmits its DL positioningreference signals 10 on a second frequency which is different from thefirst frequency. An example of a corresponding frequency hop pattern isillustrated in FIG. 2.

In the example of FIG. 2, the positions where the DL positioningreference signals 10 are transmitted are shown in terms of positions ina time-frequency grid as used for allocation of radio resources forwireless communication in the wireless communication network. Thetime-frequency grid may for example be organized in physical resourceblocks (PRBs). When utilizing the LTE radio access technology, each PRBmay correspond to 12 subcarriers in the frequency domain. However, otherways of organizing the time-frequency grid or other PRB sizes could beutilized as well. The radio interface of the UE 100 may support only amaximum bandwidth which is smaller than the system bandwidth of thewireless communication network, i.e., a maximum bandwidth supported formulti-frequency modulation, such as OFDM. For example, the maximumbandwidth supported by the radio interface may correspond to anarrowband frequency range as used for MTC or NB-IoT communication. Thenarrowband frequency range may for example correspond to six PRBs in thefrequency domain (e.g., if the UE is of MTC type) or to one PRB in thefrequency domain (e.g., if the UE is of NB-IoT type).

As further illustrated in FIG. 2, the DL positioning reference signals10 of different base stations 200 (BS1, BS2, and BS3) are multiplexed byfrequency division multiplexing, i.e., transmitted on differentfrequencies. In addition as an alternative, also time divisionmultiplexing or code division multiplexing could be utilized.

In the example of FIG. 2, the frequency hop pattern is based on a firstfrequency hop distance Df1 and a second frequency hop distance Df2. Thefirst frequency hop distance Df1 is a small frequency hop distance,e.g., smaller than the maximum bandwidth supported by the radiointerface. The second frequency hop distance Df2 is a large frequencyhop distance, e.g., larger than the maximum bandwidth supported by theradio interface, e.g., spaced apart by one or more narrowband frequencyranges. The first frequency hop distance Df1 may be used for performingcoarse positioning measurements, while the second frequency hop distanceDf2 may be used for performing fine positioning measurements. A furtherbenefit of the large frequency hop distance Df2 is that it providesrobustness against frequency selective fading (which might for exampleoccur within a frequency range corresponding to the small frequency hopdistance Df1). As shown in FIG. 2, the first frequency hop distance Df1can be one PRB (e.g., 12 sub-carriers), while the second frequency hopdistance Df2 can be six PRBs or larger. Accordingly, the first frequencyhop distance Df1 can be used for performing a frequency hop within thenarrowband frequency range, whereas the second frequency hop distanceDf2 can be used for performing a frequency hop to outside the narrowbandfrequency range or to another narrowband frequency range. Since thefrequency hop pattern is utilized for switching the radio interfacebetween different frequency ranges, changing the frequency of the DLpositioning reference signals 10 is not limited by the maximum bandwidthsupported by the radio interface and frequency diversity of the DLpositioning reference signals is enhanced beyond the narrowbandfrequency range. In this way, positioning accuracy can be improved.

As can be seen, the frequency hop pattern may be applied for offsettinga frequency division multiplexing pattern according to which the DLpositioning reference signals from the different base stations aremultiplexed. In this respect, it is noted that such frequency divisionmultiplexing pattern may also differ from the example as illustrated inFIG. 2. Further, such offsetting could also be applied with respect to amultiplexing pattern combing frequency division and time divisionmultiplexing, e.g., with respect to individual resource elements orgroups of resource elements.

It is noted that the two different frequency hop distances as explainedin the example of FIG. 2 are merely exemplary, and that it would also bepossible to utilize only one frequency hop distance or more than twofrequency hop distances. In some scenarios, one or more frequency hopdistances can also be defined in such a way that the frequency hoppattern defines frequencies which are within the same narrowbandfrequency range. A corresponding example is illustrated in FIG. 3. Whilethis may provide less frequency diversity than in the example of FIG. 2,it may be beneficial if the radio interface of the UE 100 is limited toa specific narrowband frequency range. In the example of FIG. 3, boththe first frequency hop distance Df1 and the second frequency hopdistance Df2 are smaller than the maximum bandwidth supported by theradio interface.

The frequency hop pattern may also define a repetition of the DLpositioning reference signals 10. For example, before a frequency hop,the DL positioning reference signals 10 can be repeated Y times. Ifwireless communication in the wireless communication network isorganized in subframes (like for example in the LTE radio accesstechnology), the repetitions can be defined by defining that for Ysubframes the DL positioning reference signals 10 are repeated on thesame frequency before performing a frequency hop. After the frequencyhop, the DL positioning reference signals may be repeated for Ysubframes (or another number of subframes) on another frequency. If thefrequency hop pattern defines multiple different hop distances, such asthe above-mentioned frequency hop distances Df1 and Df2, the number ofrepetitions can also be defined individually per frequency hop distance.For example, a subpattern based on the first frequency hop distance Df1could be repeated Z times before a frequency hop of the second frequencyhop distance Df2.

It is noted that the frequency hop pattern on the one hand provides theUE 100 with information on which frequency the DL positioning referencesignals 10 can be received at a given time. The UE 100 may then tune itsradio interface accordingly. On the other hand, the frequency hoppattern provides the base stations 200 with information on whichfrequency the DL positioning reference 10 signals should be transmittedat a given time. The serving base station 200 of the UE 100 mayconfigure the neighboring base stations 200 accordingly, e.g., bysending corresponding configuration information. However, since radiointerfaces of the base stations 200 typically need to supportsimultaneous transmissions over the entire system bandwidth of thewireless communication system, the base stations 200 may also transmitthe DL positioning reference signals 10 on all frequencies defined bythe frequency hop pattern. These frequencies may be distributed over theentire system bandwidth or over a subrange of the entire systembandwidth, e.g., one or more narrowband frequency ranges within thesystem bandwidth, which are assigned to be used by MTC type or NB-IoTtype devices. This may facilitate configuration of the base stations200, in particular when considering scenarios where different frequencyhop patterns, e.g., defined in a UE specific manner, need to besupported at the same time.

It is noted that the allocation of radio resources for transmission ofthe DL positioning reference signals 10 as shown in FIGS. 2 and 3 ismerely exemplary. The allocation of radio resources for transmission ofthe DL positioning reference signals 10 may be configured in variousways. This may be accomplished in a UE specific manner. Further, theallocation may also be reconfigured in a dynamic manner, e.g., to meetaccuracy requirements for the positioning measurements based on the DLpositioning reference signals 10.

For example, in some scenarios more radio resources may be allocated fortransmission of the DL positioning reference signals 10 by transmittingthe DL positioning reference signals 10 of a certain base station 200over a larger frequency range, e.g., on more subcarriers. An example ofa corresponding frequency hop pattern is illustrated in FIG. 4. Asillustrated in FIG. 4, the frequency hop pattern for the base stationBS1 is similar as in the example of FIG. 3, but additional radioresources on other frequencies are used for transmission of the DLpositioning reference signals 10.

According to a further example, in some scenarios more radio resourcesmay be allocated for transmission of the DL positioning referencesignals 10 by transmitting the DL positioning reference signals 10 of acertain base station 200 over a longer time interval, e.g., on moremodulation symbols or in more subframes. An example of a correspondingfrequency hop pattern is illustrated in FIG. 5. As illustrated in FIG.5, the frequency hop pattern for the base station BS1 is similar as inthe example of FIG. 3, but additional radio resources in other timeslots are used for transmission of the DL positioning reference signals10. The additional time domain radio resources may be used forrepetitive transmission of the UL positioning reference signal, e.g.,according to a repetition pattern as mentioned above. Alternatively orin addition, the additional time domain radio resources may be used fortransmitting the UL positioning reference signals on the basis of alonger symbol sequence.

As mentioned above, frequency division multiplexing may be used fortransmission of the DL positioning reference signals 10 of the differentbase stations. This frequency division multiplexing may be based on thesame frequency granularity as used for multi-frequency modulation (e.g.,OFDM) of wireless communication signals transmitted between the UE 100and the base stations 200. By way of example, in the LTE radio accesstechnology this frequency granularity would be defined by a subcarrierspacing of 15 kHz. In some scenarios, frequency division multiplexing ofthe DL positioning reference signals 10 may be based on a finerfrequency granularity than the frequency granularity as used formulti-frequency modulation of the wireless communication signals. Inthis way, efficiency of frequency usage may be improved. An example ofutilizing a finer frequency granularity for frequency divisionmultiplexing of the DL positioning reference signals 10 is illustratedin FIG. 6. In FIG. 6, SC denotes a spacing of subcarriers as utilizedfor multi-frequency modulation of the wireless communication signals.For example, this may correspond to the 15 kHz subcarrier spacing asused for OFDM in the LTE radio access technology. As furtherillustrated, when transmitting the DL positioning reference signals 10,a finer frequency granularity, e.g., of less than 15 kHz, such as 3.75kHz, is used for frequency division multiplexing of the DL positioningreference signals 10 of different base stations 200. The UE 100 and thebase stations 200 may switch to this finer frequency granularity in timeintervals used for transmission of the DL positioning reference signals10.

FIG. 7 schematically illustrates positioning measurements for a UE 100which are based on UL positioning reference signals 20 transmitted bythe UE 100 and received by different base stations 200 of the wirelesscommunication network. One of the base stations 200, e.g., the basestation designated with “BS1”, is assumed to be a serving base stationof the UE 100. Via the serving base station 200, the UE 100 is connectedto the wireless communication network. The other base stations 200 areassumed to be neighboring base stations.

As illustrated, the UE 100 transmits UL positioning reference signals 20which are received by the base stations 200. In a similar manner, ULpositioning reference signals may be transmitted by other UEs (notillustrated). The UL positioning reference signals 20 transmitted bydifferent UEs may be multiplexed using frequency division multiplexing,time division multiplexing, and/or code division multiplexing. The ULpositioning reference signals 20 can be based on differential operationsbetween two training symbols and may be generated based on a Zadoff-Chusequence. The UL positioning reference signals 20 may be UE-specific.

The base stations 200 receive the UL positioning reference signals 20and evaluate the received UL positioning reference signals 20. Forexample, each base station 200 may perform cross-correlation of thereceived UL positioning reference signals with locally generated signalsand thereby estimate propagation delays for the UL positioning referencesignals 20. This may also involve averaging and/or correlating multipletransmissions of the UL positioning reference signals 20. The ULpositioning reference signals 20 may be received via different antennasof the same base station 200, and the propagation delay may be estimatedbased on the UL positioning reference signals 20 received via thedifferent antennas of the same base station 200. Further, it is possibleto utilize a PDP for estimating the propagation delays of the ULpositioning reference signals 20. The serving base station 200 collectsthe estimated propagation delays from the neighboring base stations 200.For example, the serving base station 200 may configure the neighboringbase stations 200 to perform the measurements on the UL positioningreference signals 20 transmitted by the UE 100 and to report results ofthese measurements to the serving base station 200.

From the propagation delays of the UL positioning reference signals 20received by the different base stations 200, the serving base station200 may then obtain RSTD values, e.g., by subtracting the propagationdelay reported by each of the neighboring base stations 200 from thepropagation delay estimated by the serving base station 200. The servingbase station 200 then reports the measurements, e.g., the obtained RSTDvalues, to a location server (not illustrated). This may also involvereporting measurement quality. The location server may then furtherevaluate the reported measurements to determine the position of the UE100, e.g., in terms of geographical coordinates. This may for example bebased on triangulation and/or trilateration calculations.

As mentioned above, the transmission of the UL positioning referencesignals 20 is based on a frequency hop pattern. The frequency hoppattern can be configured by the wireless communication network. Thefrequency hop pattern can be base station specific, cell specific, or UEspecific. Accordingly, the UE 100 changes the frequency (f) where ittransmits the UL positioning reference signals 20 depending on the time(t). In other words, at a first time, the UE 100 transmits the ULpositioning reference signals 20 on a first frequency, while at a secondtime the UE 100 transmits the UL positioning reference signals 20 on asecond frequency which is different from the first frequency. An exampleof a corresponding frequency hop pattern is illustrated in FIG. 8.

In the example of FIG. 8, the positions where the UL positioningreference signals 20 are transmitted are shown in terms of positions ina time-frequency grid as used for allocation of radio resources forwireless communication in the wireless communication network. Thetime-frequency grid may for example be organized in physical resourceblocks (PRBs). When utilizing the LTE radio access technology, each PRBmay correspond to 12 subcarriers in the frequency domain. However, otherways of organizing the time-frequency grid other PRB sizes could beutilized as well. The radio interface of the UE 100 may support only amaximum bandwidth which is smaller than the system bandwidth of thewireless communication network, i.e., a maximum bandwidth supported formulti-frequency modulation, such as OFDM or SC-FDMA (Single CarrierFrequency Division Multiple Access). For example, the maximum bandwidthsupported by the radio interface may correspond to a narrowbandfrequency range as used for MTC for NB-IoT communication. The narrowbandfrequency range may for example correspond to six PRBs in the frequencydomain (e.g., if the UE is of MTC type) or to one PRB in the frequencydomain (e.g., if the UE is of NB-IoT type).

As further illustrated in FIG. 8, the UL positioning reference signals20 of different UEs (UE1, UE2, and UE3) are multiplexed by frequencydivision multiplexing, i.e., transmitted on different frequencies. Inaddition as an alternative, also time division multiplexing or codedivision multiplexing could be utilized. The UL positioning referencesignals 20 from a given UE may be transmitted on multiple subcarriers,e.g., spanning a PRB (12 subcarriers). However, in some scenarios a UE,e.g., the UE 100, could also send the UL positioning reference signalsusing a single tone transmission (e.g., on a single 15 kHz subcarrier).Single tone transmissions have a lower peak to average power ratio thanmulti-tone transmissions and are hence more energy efficient thanmulti-tone transmissions. Some UEs may only support single-tonetransmissions due to hardware limitations.

In the example of FIG. 8, the frequency hop pattern is based on a firstfrequency hop distance Df1 and a second frequency hop distance Df2. Thefirst frequency hop distance Df1 is a small frequency hop distance,e.g., smaller than the maximum bandwidth supported by the radiointerface. The second frequency hop distance Df2 is a large frequencyhop distance, e.g., larger than the maximum bandwidth supported by theradio interface, e.g., spaced apart by one or more narrowband frequencyranges. A further benefit of the large frequency hop distance Df2 isthat it pro-vides robustness against frequency selective fading (whichmight for ex-ample occur within a frequency range corresponding to thesmall frequency hop distance Df1). The first frequency hop distance Df1may be used for performing coarse positioning measurements, while thesecond frequency hop distance Df2 may be used for performing finepositioning measurements. As shown in FIG. 8, the first frequency hopdistance Df1 can be one PRB (e.g., 12 subcarriers), while the secondfrequency hop distance Df2 can be six PRBs or larger. Accordingly, thefirst frequency hop distance Df1 can be used for performing a frequencyhop within the narrowband frequency range, whereas the second frequencyhop distance Df2 can be used for performing a frequency hop to outsidethe narrowband frequency range or to another narrowband frequency range.Since the frequency hop pattern is utilized for switching the radiointerface between different frequency ranges, changing the frequency ofthe UL positioning reference signals 20 is not limited by the maximumbandwidth supported by the radio interface and frequency diversity ofthe UL positioning reference signals is enhanced beyond the narrowbandfrequency range. In this way, positioning accuracy can be improved.

As can be seen, the frequency hop pattern may be applied for offsettinga frequency division multiplexing pattern according to which the ULpositioning reference signals from the different UEs are multiplexed. Inthis respect, it is noted that such frequency division multiplexingpattern may also differ from the example as illustrated in FIG. 8.Further, such offsetting could also be applied with respect to amultiplexing pattern combing frequency division and time divisionmultiplexing, e.g., with respect to individual resource elements orgroups of resource elements.

It is noted that the two different frequency hop distances as explainedin the example of FIG. 8 are merely exemplary, and that it would also bepossible to utilize only one frequency hop distance or more than twofrequency hop distances. In some scenarios, one or more frequencydistances can also be defined in such a way that the frequency hoppattern defines frequencies which are within the same narrowbandfrequency range. A corresponding example is illustrated in FIG. 9. Whilethis may provide less frequency diversity than in the example of FIG. 8,it may be beneficial if the radio interface of the UE 100 is limited toa specific narrowband frequency range. In the example of FIG. 9, boththe first frequency hop distance Df1 and the second frequency hopdistance Df2 are smaller than the maximum bandwidth supported by theradio interface.

The frequency hop pattern may also define a repetition of the ULpositioning reference signals 20. For example, before a frequency hop,the UL positioning reference signals 20 can be repeated Y times. Ifwireless communication in the wireless communication is organized insubframes (like for example in the LTE radio access technology), therepetitions can be defined by defining that for Y subframes the ULpositioning reference signals 10 are repeated on the same frequencybefore performing a frequency hop. After the frequency hop, the ULpositioning reference signals 20 may be repeated for Y subframes (oranother number of subframes) on another frequency. If the frequency hoppattern defines multiple different hop distances, such as theabove-mentioned frequency hop distances Df1 and Df2, the number ofrepetitions can also be defined individually per frequency hop distance.For example, a subpattern based on the first frequency hop distance Df1could be repeated Z times before a frequency hop of the second frequencyhop distance Df2.

It is noted that the frequency hop pattern on the one hand provides theUE 100 with information on which frequency it should transmit the ULpositioning reference signals 20 at a given time. The UE 100 may thentune its radio interface accordingly. On the other hand, the frequencyhop pattern provides the base stations 200 with information on whichfrequency the UL positioning reference signals 20 from the UE 100 can bereceived at a given time. The serving base station 200 of the UE 100 mayconfigure the neighboring base stations 200 accordingly, e.g., bysending corresponding configuration information.

It is noted that the allocation of radio resources for transmission ofthe UL positioning reference signals 20 as shown in FIGS. 8 and 9 ismerely exemplary. The allocation of radio resources for transmission ofthe UL positioning reference signals 20 may be configured in variousways. This may be accomplished in a UE specific manner. Further, theallocation may also be reconfigured in a dynamic manner, e.g., to meetaccuracy requirements for the positioning measurements based on the ULpositioning reference signals 20.

For example, in some scenarios more radio resources may be allocated fortransmission of the UL positioning reference signals 20 by transmittingthe UL positioning reference signals 20 of the UE 100 over a largerfrequency range, e.g., on more subcarriers. An example of acorresponding frequency hop pattern is illustrated in FIG. 10. Asillustrated in FIG. 10, the frequency hop pattern for UE1 is similar asin the example of FIG. 9, but additional radio resources on otherfrequencies are used for transmission of the UL positioning referencesignals 20.

According to a further example, in some scenarios more radio resourcesmay be allocated for transmission of the UL positioning referencesignals 20 by transmitting the UL positioning reference signals 20 ofthe UE 100 over a longer time interval, e.g., on more modulation symbolsor in more subframes. An example of a corresponding frequency hoppattern is illustrated in FIG. 11. As illustrated in FIG. 11, thefrequency hop pattern for UE1 is similar as in the example of FIG. 9,but additional radio resources in other time slots are used fortransmission of the UL positioning reference signals 20. The additionaltime domain radio resources may be used for repetitive transmission ofthe UL positioning reference signal, e.g., according to a repetitionpattern as mentioned above. Alternatively or in addition, the additionaltime domain radio resources may be used for transmitting the ULpositioning reference signals on the basis of a longer symbol sequence.

As mentioned above, frequency division multiplexing may be used fortransmission of the UL positioning reference signals 20 of the differentUEs. This frequency division multiplexing may be based on the samefrequency granularity as used for multi-frequency modulation (e.g., OFDMor SC-FDMA) of wireless communication signals transmitted between the UE100 and the base stations 200. By way of example, in the LTE radioaccess technology this frequency granularity would be defined by asubcarrier spacing of 15 kHz. In some scenarios, frequency divisionmultiplexing of the UL positioning reference signals 20 may be based ona finer frequency granularity than the frequency granularity as used formulti-frequency modulation of the wireless communication signals. Inthis way, efficiency of frequency usage may be improved. An example ofutilizing a finer frequency granularity for frequency divisionmultiplexing of the UL positioning reference signals 20 is illustratedin FIG. 12. In FIG. 12, SC denotes a spacing of subcarriers as utilizedfor multi-frequency modulation of the wireless communication signals.For example, this may correspond to the 15 kHz subcarrier spacing asused for OFDM or SC-FDMA in the LTE radio access technology. As furtherillustrated, when transmitting the UL positioning reference signals 20,a finer frequency granularity, e.g., of less than 15 kHz, such as 3.75kHz, is used for frequency division multiplexing of the UL positioningreference signals 20 of UEs. The UE 100 and the base stations 200 mayswitch to this finer frequency granularity in time intervals used fortransmission of the UL positioning reference signals 20.

While in the above examples the UL positioning reference signals 20 areutilized for positioning measurements, other utilizations are possibleas well. For example, one or more of the base stations 200 may utilizethe UL positioning reference signals 24 for estimating channel qualityand/or channel sounding for the UE 100.

Further, it is noted that measurements based on the above-mentioned DLpositioning reference signals 10 and the above-mentioned UL positioningreference signals 20 may also be combined. For example, results obtainedfrom both types of measurements may be reported to the location serverand then be used in combination for determining the position of the UE100.

FIG. 13 shows a flowchart illustrating a method which may be used forenabling positioning measurements for a wireless communication device,e.g., the above-mentioned UE 100, in a wireless communication network,e.g., a cellular network. By the method of FIG. 13 the wirelesscommunication device, e.g., the above-mentioned UE 100, may implementthe above described concepts involving positioning measurements based onDL positioning reference signals. If a processor based implementation ofthe wireless communication device is utilized, at least a part of thesteps of the method may be performed and/or controlled by one or moreprocessors of the wireless communication device.

At step 1310, a frequency hop pattern is configured. The frequency hoppattern is to be applied by the wireless communication device forreceiving DL positioning reference signals from base stations of awireless communication network, e.g., from the above-mentioned basestations 200. The DL positioning reference signals may for examplecorrespond to the abovementioned DL positioning reference signals 10.Examples of frequency hop patterns are illustrated in FIGS. 2, 3, 4, and5.

The DL positioning reference signals transmitted by different basestations may be multiplexed on the basis of a multiplexing schemecomprising one or more of frequency division multiplexing, time divisionmultiplexing, and code division multiplexing. In some scenarios, afrequency granularity for frequency division multiplexing of the DLpositioning reference signals transmitted by different base stations maybe finer than a frequency granularity for frequency divisionmultiplexing of wireless communication signals transmitted between thewireless communication device and the wireless communication network,e.g., as explained in connection with FIG. 6. It is noted that whendifferent base stations apply the same frequency hop pattern, thefrequency division multiplexing may result in different frequencies fortransmission of the DL positioning reference signals. In other words,the frequency hop pattern may be applied for offsetting a frequencydivision multiplexing pattern according to which the DL positioningreference signals from the different base stations are multiplexed.

The wireless communication device may configure the frequency hoppattern on the basis of configuration information received from thewireless communication network, e.g., from one of the base stations. Forexample, a serving base station of the wireless communication devicecould determine the frequency hop pattern and send correspondingconfiguration information to the wireless communication device. Further,a location server could determine the frequency hop pattern and sendcorresponding configuration information to the wireless communicationdevice, e.g., via a serving base station of the wireless communicationdevice. However, the frequency hop pattern could also be configured onthe basis of information stored in the wireless communication device,e.g., as part of factory settings or operator settings. Further, in somecases the wireless communication network could also locally configurethe frequency hop pattern and then indicate the frequency hop pattern tothe wireless communication network, e.g., by sending correspondingconfiguration information to a base station of the wirelesscommunication network.

In some scenarios, the frequency hop pattern may further define arepetition pattern of the DL positioning reference signals. In otherwords, the frequency hop pattern may then be defined in terms of asequence of frequency hops and repetitions of the DL positioningreference signals between the frequency hops. The frequency hops may bebased on the same frequency hop distance or on multiple differentfrequency hop distances.

At step 1320 the wireless communication device switches a radiointerface of the wireless communication device between multipledifferent frequency ranges to receive the DL positioning referencesignals on multiple different frequencies defined by the frequency hoppattern. This switching is accomplished according to the frequency hoppattern configured at step 1310. Accordingly, for each of the differentfrequencies, the wireless communication device may tune its radiointerface to another frequency range. In this way, the DL positioningreference signals can be received with high accuracy. Further, frequencydiversity of the DL positioning reference signals can be enhancedirrespective of bandwidth limitations of the radio interface of thewireless communication device.

At least some of the multiple different frequencies may be separated bymore than a maximum bandwidth supported by the radio interface of thewireless communication device. In some scenarios, the frequency hoppattern may define a first frequency hop distance which is smaller thanthe maximum bandwidth supported by the radio interface and a secondfrequency hop distance, e.g., as explained in connection with FIG. 2.

At step 1330, the wireless communication device determines positioninginformation for the wireless communication device. This is accomplishedby combined evaluation of the received DL positioning reference signals.In particular, positioning accuracy can be improved by considering DLpositioning reference signals received on different frequencies. Thepositioning information may include a time-difference of arrival (TDOA)of the DL positioning reference signals from multiple different basestations. However, other kinds of positioning information could bedetermined as well, e.g., a time of arrival (TOA), an angle of arrival(AOA), and/or Doppler shift based information. When using an AOA,measurements on a single DL positioning reference signal could besufficient to determine the position of the wireless communicationdevice. In some scenarios, the positioning information could alsoinclude the position of the wireless communication device in absolutegeographical coordinates or in coordinates relative to the basestations. The wireless communication device may then report thepositioning information to a location server.

FIG. 14 shows a flowchart illustrating a method which may be used forenabling positioning measurements for a wireless communication device,e.g., the above-mentioned UE 100, in a wireless communication network,e.g., a cellular network. By the method of FIG. 14, a base station ofthe wireless communication network, e.g., the above-mentioned basestation 200, may implement the above described concepts involvingpositioning measurements based on DL positioning reference signals. If aprocessor based implementation of the base station is utilized, at leasta part of the steps of the method may be performed and/or controlled byone or more processors of the base station.

At step 1410, a frequency hop pattern is configured. The frequency hoppattern is to be applied by the wireless communication device forreceiving DL positioning reference signals from base stations of awireless communication network, e.g., from the above-mentioned basestations 200. The DL positioning reference signals may for examplecorrespond to the abovementioned DL positioning reference signals 10.Examples of frequency hop patterns are illustrated in FIGS. 2, 3, 4, and5.

The DL positioning reference signals transmitted by different basestations may be multiplexed on the basis of a multiplexing schemecomprising one or more of frequency division multiplexing, time divisionmultiplexing, and code division multiplexing. In some scenarios, afrequency granularity for frequency division multiplexing of the DLpositioning reference signals transmitted by different base stations maybe finer than a frequency granularity for frequency divisionmultiplexing of wireless communication signals transmitted between thewireless communication device and the wireless communication network,e.g., as explained in connection with FIG. 6. It is noted that whendifferent base stations apply the same frequency hop pattern, thefrequency division multiplexing may result in different frequencies fortransmission of the DL positioning reference signals. In other words,the frequency hop pattern may be applied for offsetting a frequencydivision multiplexing pattern according to which the DL positioningreference signals from the different base stations are multiplexed.

For configuring the frequency hop pattern, the base station may sendconfiguration information indicating the frequency hop pattern to thewireless communication device. However, in some cases the base stationcould, additionally or alternatively, also configure the frequency hoppattern based on configuration information received from the wirelesscommunication device. For example, the wireless communication devicecould locally configure the frequency hop pattern and then indicate thefrequency hop pattern by sending corresponding configuration informationto the base station. Further, a location server could determine thefrequency hop pattern and send corresponding configuration informationto the base station.

In some scenarios, the frequency hop pattern may further define arepetition pattern of the DL positioning reference signals. In otherwords, the frequency hop pattern may then be defined in terms of asequence of frequency hops and repetitions of the DL positioningreference signals between the frequency hops. The frequency hops may bebased on the same frequency hop distance or on multiple differentfrequency hop distances.

At least some of the multiple different frequencies may be separated bymore than a maximum bandwidth supported by the radio interface of thewireless communication device. In some scenarios, the frequency hoppattern may define a first frequency hop distance which is smaller thanthe maximum bandwidth supported by the radio interface and a secondfrequency hop distance which is larger than the maximum bandwidthsupported by the radio interface, e.g., as explained in connection withFIG. 2.

At step 1420, the base station sends a first part of the DL positioningreference signals according to the frequency hop pattern. This mayinvolve time dependent changing of the frequency on which the basestation sends the DL positioning reference signals. However, the basestation could also send the DL positioning reference signalssimultaneously on the multiple different frequencies defined by thefrequency hop pattern, e.g., on frequencies distributed over the entiresystem bandwidth of the wireless communication network or over a certainsubrange within the system bandwidth of the wireless communicationnetwork.

At step 1430, the base station configures further base stations of thewireless communication network to send a second part of the DLpositioning reference signals according to the frequency hop pattern.This may involve that the base stations sends configuration informationindicating the frequency hop pattern to the further base stations. Thefurther base stations may for example be neighboring base stations.Sending of the second part of the DL positioning reference signals bythe further base stations may involve that each of the further basestations changes the frequency on which it sends the DL positioningreference signals in a time-dependent manner. However, the further basestation could also send the DL positioning reference signalssimultaneously on the multiple different frequencies defined by thefrequency hop pattern, e.g., on frequencies distributed over the entiresystem bandwidth of the wireless communication network or over a certainsubrange within the system bandwidth of the wireless communicationnetwork.

FIG. 15 shows a flowchart illustrating a method which may be used forenabling positioning measurements for a wireless communication device,e.g., the above-mentioned UE 100, in a wireless communication network,e.g., a cellular network. By the method of FIG. 15 the wirelesscommunication device, e.g., the above-mentioned UE 100, may implementthe above described concepts involving positioning measurements based onUL positioning reference signals. If a processor based implementation ofthe wireless communication device is utilized, at least a part of thesteps of the method may be performed and/or controlled by one or moreprocessors of the wireless communication device.

At step 1510, a frequency hop pattern is configured. The frequency hoppattern is to be applied for sending UL positioning reference signalsfrom the wireless communication device. The UL positioning referencesignals may for example correspond to the above-mentioned UL positioningreference signals 20. Examples of frequency hop patterns are illustratedin FIGS. 8, 9, 10, and 11.

The UL positioning reference signals transmitted by different wirelesscommunication devices, i.e., by the wireless communication device andone or more further wireless communication devices, may be multiplexedon the basis of a multiplexing scheme comprising one or more offrequency division multiplexing, time division multiplexing, and codedivision multiplexing. In some scenarios, a frequency granularity forfrequency division multiplexing of the UL positioning reference signalstransmitted by different wireless communication devices may be finerthan a frequency granularity for frequency division multiplexing ofwireless communication signals transmitted between the wirelesscommunication device and the wireless communication network, e.g., asexplained in connection with FIG. 12. It is noted that when differentwireless communication devices apply the same frequency hop pattern, thefrequency division multiplexing may result in different frequencies fortransmission of the respective UL positioning reference signals. Inother words, the frequency hop pattern may be applied for offsetting afrequency division multiplexing pattern according to which the ULpositioning reference signals from the different wireless communicationdevices are multiplexed.

The wireless communication device may configure the frequency hoppattern on the basis of configuration information received from thewireless communication network, e.g., from a base station of thewireless communication network. For example, a serving base station ofthe wireless communication device could determine the frequency hoppattern and send corresponding configuration information to the wirelesscommunication device. Further, a location server could determine thefrequency hop pattern and send corresponding configuration informationto the wireless communication device, e.g., via a serving base stationof the wireless communication device. However, the frequency hop patterncould also be configured on the basis of information stored in thewireless communication device, e.g., as part of factory settings oroperator settings. Further, in some cases the wireless communicationnetwork could also locally configure the frequency hop pattern and thenindicate the frequency hop pattern to the wireless communicationnetwork, e.g., by sending corresponding configuration information to abase station of the wireless communication network.

In some scenarios, the frequency hop pattern may further define arepetition pattern of the UL positioning reference signals. In otherwords, the frequency hop pattern may then be defined in terms of asequence of frequency hops and repetitions of the UL positioningreference signals between the frequency hops. The frequency hops may bebased on the same frequency hop distance or on multiple differentfrequency hop distances.

At step 1520, the wireless communication device switches a radiointerface of the wireless communication device between multipledifferent frequency ranges to send the UL positioning reference signalson multiple different frequencies defined by the frequency hop pattern.This is accomplished according to the frequency hop pattern asconfigured at step 1510. Sending of the UL positioning reference signalsby the wireless communication device may involve time dependent changingof the frequency on which the wireless communication device sends the ULpositioning reference signals. Accordingly, for each of the differentfrequencies, the wireless communication device may tune its radiointerface to another frequency range. In this way, the UL positioningreference signals can be transmitted with enhanced frequency diversity,irrespective of bandwidth limitations of the radio interface of thewireless communication device.

At least some of the multiple different frequencies may be separated bymore than a maximum bandwidth supported by the radio interface of thewireless communication device. In some scenarios, the frequency hoppattern may define a first frequency hop distance which is smaller thanthe maximum bandwidth supported by the radio interface and a secondfrequency hop distance which is larger than the maximum bandwidthsupported by the radio interface, e.g., as explained in connection withFIG. 8.

FIG. 16 shows a flowchart illustrating a method which may be used forenabling positioning measurements for a wireless communication device,e.g., the above-mentioned UE 100, in a wireless communication network,e.g., a cellular network. By the method of FIG. 16, a base station ofthe wireless communication network, e.g., the above-mentioned basestation 200, may implement the above described concepts involvingpositioning measurements based on UL positioning reference signals. If aprocessor based implementation of the base station is utilized, at leasta part of the steps of the method may be performed and/or controlled byone or more processors of the base station.

At step 1610, a frequency hop pattern is configured. The frequency hoppattern is to be applied for sending UL positioning reference signalsfrom the wireless communication device. The UL positioning referencesignals may for example correspond to the above-mentioned UL positioningreference signals 20. Examples of frequency hop patterns are illustratedin FIGS. 8, 9, 10, and 11.

The UL positioning reference signals transmitted by different wirelesscommunication devices, i.e., by the wireless communication device andone or more further wireless communication devices, may be multiplexedon the basis of a multiplexing scheme comprising one or more offrequency division multiplexing, time division multiplexing, and codedivision multiplexing. In some scenarios, a frequency granularity forfrequency division multiplexing of the UL positioning reference signalstransmitted by different wireless communication devices may be finerthan a frequency granularity for frequency division multiplexing ofwireless communication signals transmitted between the wirelesscommunication device and the wireless communication network, e.g., asexplained in connection with FIG. 12. It is noted that when differentwireless communication devices apply the same frequency hop pattern, thefrequency division multiplexing may result in different frequencies fortransmission of the respective UL positioning reference signals. Inother words, the frequency hop pattern may be applied for offsetting afrequency division multiplexing pattern according to which the ULpositioning reference signals from the different wireless communicationdevices are multiplexed.

For configuring the frequency hop pattern, the base station may sendconfiguration information indicating the frequency hop pattern to thewireless communication device. However, in some cases the base stationcould also configure the frequency hop pattern based on configurationinformation received from the wireless communication device. Forexample, the wireless communication network could locally configure thefrequency hop pattern and then indicate the frequency hop pattern bysending corresponding configuration information to the base station.Further, a location server could determine the frequency hop pattern andsend corresponding configuration information to base station.

In some scenarios, the frequency hop pattern may further define arepetition pattern of the UL positioning reference signals. In otherwords, the frequency hop pattern may then be defined in terms of asequence of frequency hops and repetitions of the UL positioningreference signals between the frequency hops. The frequency hops may bebased on the same frequency hop distance or on multiple differentfrequency hop distances.

At step 1620, the base station receives the UL positioning referencesignals from the wireless communication device. For this purpose, thebase station may monitor the frequencies defined by the frequency hoppattern.

At step 1630, the base station configures further base stations of thewireless communication network to receive the UL positioning referencesignals from the wireless communication device. This may involve thatthe base stations sends configuration information indicating thefrequency hop pattern to the further base stations. The further basestations may for example be neighboring base stations. For receiving theUL positioning reference signals, each of the further base stations maymonitor the frequencies defined by the frequency hop pattern. Further,the base station configures the further base stations to provideinformation derived from the received UL positioning reference signalsto the base station, e.g., by requesting measurement reports.

At step 1640, the base station determines positioning information forthe wireless communication device. This is accomplished by combinedevaluation of the UL positioning reference signals received at step 1620and the information provided by the further base stations. Thepositioning information may include a time-difference of arrival (TDOA)of the UL positioning reference signals between different base stationsreceiving the UL positioning reference signals. However, other kinds ofpositioning information could be determined as well, e.g., a time ofarrival (TOA), an angle of arrival (AOA), and/or Doppler shift basedinformation. When using an AOA, measurements on a single DL positioningreference signal could be sufficient to determine the position of thewireless communication device. In some scenarios, the positioninginformation could also include the position of the wirelesscommunication device in absolute geographical coordinates or incoordinates relative to the base stations. The base station may thenreport the positioning information to a location server.

It is to be understood that the methods of FIGS. 13, 14, 15, and/or 16may also be combined, e.g., in a system including at least one wirelesscommunication device operating according to the method of FIG. 13 and atleast one base station operating according to the method of FIG. 14, orin a system including at least one wireless communication deviceoperating according to the method of FIG. 15 and at least one basestation operating according to the method of FIG. 16. Further, the samewireless communication device could implement both the method of FIG. 13and the method of FIG. 15, and/or the same base station could implementboth the method of FIG. 14 and the method of FIG. 16.

Further, it is noted that the method steps of FIGS. 13, 14, 15, and/or16 do not necessarily need to be performed in the illustrated order andthat different order of the illustrated steps are possible or some ofthe illustrated steps could be performed in parallel. Further,individual actions or operations of different steps could be performedin an interleaved manner.

FIG. 17 shows a block diagram for schematically illustrating a processorbased implementation of a wireless communication device which may beutilized for implementing the above concepts. The wireless communicationdevice may for example correspond to a UE, such as the above-mentionedUE 100.

As illustrated, the wireless communication device includes a radiointerface 110. The wireless communication device may utilize the radiointerface 110 for connecting to a wireless communication network, e.g.,through a base station of the wireless communication network, such asone of the base stations 200.

Further, the wireless communication device is provided with one or moreprocessors 140 and a memory 150. The radio interface 110 and the memory150 are coupled to the processor(s) 140, e.g., using one or moreinternal bus systems of the wireless communication device.

The memory 150 includes program code modules 160, 170 with program codeto be executed by the processor(s) 140. In the illustrated example,these program code modules include a communication control module 160and a positioning management module 170.

The communication control module 160 may implement functionalities ofcontrolling wireless transmissions between the wireless communicationdevice and the wireless communication network. The positioningmanagement module 170 may implement the above-described functionalitiesof utilizing a frequency hop pattern for enabling positioningmeasurements, e.g., according to the method of FIG. 13 and/or the methodof FIG. 15.

It is to be understood that the structures as illustrated in FIG. 17 aremerely exemplary and that the wireless communication device may alsoinclude other elements which have not been illustrated, e.g., structuresor program code modules for implementing known functionalities of a UEor other type of wireless communication device.

FIG. 18 shows a block diagram for schematically illustrating a processorbased implementation of a base station which may be utilized forimplementing the above concepts. The base station may for examplecorrespond to one of the above-mentioned base stations 200.

As illustrated, the base station includes a radio interface 210. Thebase station may utilize the radio interface 210 for connecting to atleast one wireless communication device, e.g., a UE such as the UE 100.Further, the base station includes a network interface 220. The basestation may utilize the network interface 220 for connecting to othernodes of the wireless communication network, in particular to other basestations.

Further, the base station is provided with one or more processors 240and a memory 250. The radio interface 210, the network interface 220,and the memory 250 are coupled to the processor(s) 240, e.g., using oneor more internal bus systems of the base station.

The memory 250 includes program code modules 260, 270 with program codeto be executed by the processor(s) 240. In the illustrated example,these program code modules include a communication control module 260and a positioning management module 270.

The communication control module 260 may implement functionalities ofcontrolling wireless transmissions between a wireless communicationdevice and the wireless communication network. The positioningmanagement module 270 may implement the above-described functionalitiesof utilizing a frequency hop pattern for enabling positioningmeasurements, e.g., according to the method of FIG. 14 and/or the methodof FIG. 16.

It is to be understood that the structures as illustrated in FIG. 18 aremerely exemplary and that the base station may also include otherelements which have not been illustrated, e.g., structures or programcode modules for implementing known functionalities of a base station.

It is to be understood that the concepts as explained above aresusceptible to various modifications. For example, the concepts could beapplied in connection with various kinds of wireless communicationtechnologies and devices. Further, the concepts may be applied inconnection with various types of algorithms for evaluating the DLpositioning reference signals and/or UL positioning reference signals.

1. A method of enabling position measurement for a wireless communication device, the method comprising: configuring a frequency hop pattern to be applied for switching a radio interface of the wireless communication device between multiple different frequency ranges to send uplink positioning reference signals on multiple different frequencies defined by the frequency hop pattern; receiving, by a base station of a wireless communications network, the uplink positioning reference signals from the wireless communication device; configuring further base stations of the wireless communications network to receive the uplink positioning references signals from the wireless communications device and to provide information derived from received uplink positioning reference signals to the base station; and by combined evaluation of received uplink positioning reference signals and the information provided by the further base stations, determining positioning information for the wireless communication device.
 2. The method according to claim 1, wherein the wireless communication device configures the frequency hop pattern on the basis of configuration information received from the wireless communication network. 3-9. (canceled)
 10. The method according to claim 1, wherein the base station sends configuration information indicating the frequency hop pattern to the wireless communication device.
 11. The method according to claim 1, wherein the base station sends configuration information indicating the frequency hop pattern to the further base stations.
 12. (canceled)
 13. The method according to claim 1, wherein the frequency hop pattern defines a first frequency hop distance which is smaller than the maximum bandwidth supported by the radio interface and a second frequency hop distance which is larger than the maximum bandwidth supported by the radio interface.
 14. The method according to claim 1, wherein the frequency hop pattern further defines a repetition pattern of the uplink positioning reference signals.
 15. The method according to claim 1, wherein the uplink positioning reference signals are multiplexed on the basis of a frequency multiplexing scheme.
 16. The method according to claim 15, wherein a frequency granularity for frequency division multiplexing of the uplink positioning reference signals is finer than a frequency granularity for frequency division multiplexing of wireless communication signals transmitted between the wireless communication device and the wireless communication network. 17-21. (canceled)
 22. The method according to claim 15, wherein the multiplexing scheme comprises one or more of frequency division multiplexing, time division multiplexing, and code division multiplexing. 23-30. (canceled)
 31. The method according to claim 15, wherein the uplink positioning reference signals and further uplink positioning reference signals transmitted by one or more other wireless communication devices are multiplexed on the basis of a multiplexing scheme comprising one or more of frequency division multiplexing, time division multiplexing, and code division multiplexing.
 32. The method according to claim 31, wherein a frequency granularity for frequency division multiplexing of the uplink positioning reference signals and the further uplink positioning reference signals transmitted by further wireless communication devices is finer than a frequency granularity for frequency division multiplexing of wireless communication signals transmitted between the wireless communication device and the wireless communication network.
 33. A wireless communication device, comprising: a radio interface for connecting to a wireless communication network; and at least one processor, the at least one processor being configured to: configure a frequency hop pattern to be applied for switching a radio interface of the wireless communication device between multiple different frequency ranges to send uplink positioning reference signals on multiple different frequencies defined by the frequency hop pattern, wherein at least some of the multiple different frequencies are separated by more than a maximum bandwidth supported by the radio interface of the wireless communication device.
 34. (canceled)
 35. A base station for a wireless communication network, the base station comprising: a radio interface for connecting to a wireless communication device; a network interface for connecting to further base stations of the wireless communication network; and at least one processor, the at least one processor being configured to: configure a frequency hop pattern to be applied for switching a radio interface of the wireless communication device between multiple different frequency ranges to send uplink positioning reference signals on multiple different frequencies defined by the frequency hop pattern.
 36. (canceled)
 37. A system, comprising: a base station according to claim 35; and the wireless communication device. 38-42. (canceled)
 43. The method according to claim 1, further comprising: according to the frequency hop pattern, the wireless communication device switching the radio interface of the wireless communication device between the multiple different frequency ranges to send the uplink positioning reference signals on the multiple different frequencies defined by the frequency hop pattern.
 44. The method according to claim 1, wherein the positioning information comprises a time-difference of arrival of the uplink positioning reference signals at multiple different base stations.
 45. The method according to claim 1, wherein at least some of the multiple different frequencies are separated by more than a maximum bandwidth supported by the radio interface of the wireless communication device.
 46. The base station according to claim 35, wherein the at least one processor is further configured to: receive the uplink positioning reference signals from the wireless communication device; configure further base stations of the wireless communication network to receive the uplink positioning reference signals from the wireless communication device and provide information derived from the received uplink positioning reference signals to the base station; and by combined evaluation of the received uplink positioning reference signals and the information provided by the further base stations, determine positioning information for the wireless communication device.
 47. The method according to claim 46, wherein the positioning information comprises a time-difference of arrival of the uplink positioning reference signals at multiple different base stations.
 48. The base station according to claim 35, wherein at least some of the multiple different frequencies are separated by more than a maximum bandwidth supported by the radio interface of the wireless communication device. 